PESTS OF ORCHARD AND FRUIT GARDEN. 



11 



sporules (8 /x long) are expelled when mature, and in some places it is 

 looked upon with suspicion. 



Apple-tree Canker. 

 Nectria ditissima (Tul.), PI. X. fig. 6. 



Ten or twelve years since R. Goethe propounded the opinion that canker 

 on Apple trees was produced by the growth of the above-named fungus, 

 which is of the Sphceria kind, a little resembling those clusters of red 

 Nectria which are so common on Currant twigs, but smaller. Goethe 

 claims to have demonstrated his position by cultivating the parasite both 

 from conidia and ascospores. The same fungus he contends produces 

 canker on various kinds of Pear trees, and the sporidia of the Nectria 

 from the Apple were found to produce canker on the Beech and Sycamore, 

 and again from these trees on the Apple. 



According to Hartig the fungus enters through wounds caused by 

 hail or the puncture of an insect. The best remedy, according to these 

 authorities, is to cut out the diseased tissues and anoint carefully with coal 

 tar. 



The fungus consists of a number of little red dots, scarcely so large as 

 a pin's head, growing in clusters in cracks of the bark. These minute 

 dots are spherical and smooth, seated on a white mycelium, and when 

 mature enclosing a kind of pulpy nucleus, like a tiny drop of gelatin, and 

 which consists of a great number of long cylindrical tubes, or asci, each 

 enclosing a row of eight elliptical sporidia, which are divided by a trans- 

 verse septum into two cells. When ripe they are capable of germination 

 from each cell (14 x 5-6 fi). 



Occurs in France and Germany. 



GarcL Chroii. March 8 and April 19, 1884, p. 313 ; 1891, p. 300, figs. 

 66, 67 ; Sacc. Syll. ii. 4671 ; Mass. PL Dis. 127, fig. 24 ; Grevillea, ix. 

 p. 116 ; Tubeuf, Dis. p. 187, figs. 



Apple -bark Valsa. 

 Valsa ambiens (Fr.), PI. X. fig. 7. 



It is only during the past year or two that we have become satisfied 

 that this usually saprophytic fungus has seriously affected living Apple 

 trees — at least during its early or conidial condition. 



The bark of living branches and trunks was observed to be roughened 

 with little elevations from the apex of which proceeded what appeared to 

 be a long twisted yellow filament, not thicker than a horse-hair, entangled 

 together into a mass of golden threads. When moistened these threads 

 dissolved into myriads of minute curved conidia (5 jj. long) which had 

 oozed out from minute punctures of the bark, and proved to be those of a 

 fungus called Cytospora ca/rpkosperma, common on many orchard trees, 

 but heretofore considered saprophytic. 



The mature condition is to be found in spring on branches that have 

 lain on the ground through the winter, and consists of clusters of 

 receptacles, flask-shaped, with long converging necks, containing sporidia 



